The US Preventive Services Task Force recommends that all primary care physicians assess the sexually transmitted disease/human immunodeficiency virus (STD/HIV) risk of all adolescent and adult patients. To determine whether factors amenable to change through continuing medical education are associated with frequent and thorough STD/HIV risk assessment, a telephone survey of primary care physicians in the Washington, DC metropolitan area was conducted (n = 961). Thirty-seven percent of physicians reported regularly asking new adult patients about their sexual practices; 60% asked new adolescent patients. STD/HIV risk questioning was associated with physicians' confidence in their ability to help prevent HIV, comfort with discussing patients' sexual practices, and perception of a large STD/HIV problem in their practice. These findings suggest that continuing medical education should target improvement in physicians' sexual practice questioning skills.